This proposal is a request for funds to purchase a Coulter EPICS V Flow Cytometer. This is a versatile fluorescence-activated cell sorter system which is not presently available to the highly productive research groups on the University of Tennessee Medical Center campus. The flow cytometer, together with highly specific antibody or chemical probes, allows identification and purification of various cell populations not obtainable by other methods. The research programs of the major users group include studies of immune responses to infectious agents, studies of lymphokines and their roles in inflammatory and degenerative diseases, evaluation of cells bearing insulin receptors, studies of cells generating reactive oxygen species in the lung, collagenases and collagen metabolism, and the pathogenesis of multiple sclerosis. These research programs have reached a stage where the technology provided by a flow cytometer has become critical for the investigators to achieve their research objectives.